Hammer screen



Search Room 241. SOLID MATERIAL COMMINUTION 76 OR DISINTEGRATION Jan.16, 1940. v. F. LARSON HAMMER SCREEN Filed July 12, 1937 Inven 25-07"I'cor J". [6U15'07W Patented Jan. 16, 1940 UNITED STATES Search RoomPATENT OFFICE HAMIWER SCREEN Victor F. Larson, Milwaukee, Wis., assignorto Nordberg Manufacturing Company, Milwaukee, Wis., a corporation ofWisconsin Application July 12, 1937, Serial No. 153,150

4 Claims.

My invention relates to an improvement in screens and has for onepurpose the provision of a screen which shall include crushing orbreakmg means.

Another purpose is the provision of a screen which is operable uponrelatively easily broken materials whereby oversize particles may bepartially reduced as they travel to or across the screening area orareas.

Other purposes will appear from time to time in the course of thespecification and claims.

I illustrate my invention more or less diagrammatically in theaccompanying drawing wherein:

Figure 1 is a side elevation with parts in section; and

Figure 2 is a section on an enlarged scale along the line 22 of Figure1.

Like parts are indicated by like symbols throughout the specificationand drawing.

Referring to the drawing, I, 2 generally indicate side frame members ofa main frame or base herein shown as channels having outwardly extendingflanges. 3, 4 are transverse frame members connecting the side framemembers I and 2 together. 5, 6 indicate side bars or weights which havesecured to them at one end a feed box structure generally indicated asl, the details of which do not of themselves form part of the presentinvention. At the opposite end they may be secured together by anysuitable transverse structure including the transverse rod or bar 8.

9 indicates the shaft of a rotor to which is secured a pulley Ill. Therotor is journaled or suitably mounted in any suitable housing structuregenerally indicated as ll. 12 is a motor which may be mounted on themain frame or base member 4. It has a drive pulley I3 which may beconnected as by belts It to the rotor pulley II]. It will be understoodthat any suitable eccentric or vibrating means may be associated withthe shaft 9 or the pulley l 0, the details of which form no part of thepresent invention.

The housing member or members II are secured as by generally horizontalleaf springs l5, 16 to the screen structure which is below described. Itwill be understood that the side bars are movably mounted upon the baseor main frame as by a plurality of upwardly extending leaf springs l1,I! which are shown as secured at their upper ends as at I8 to the sidebars 5 and 8 and at their lower ends as at [9 to the side frame membersI or 2.

The-screen structure or deck may include side frame members 2|], 2|suitably secured to each other by any suitable transversely extendingstructural members 22. The screen deck is also movably mounted on themain frame as by the upwardly inclined springs 23. It will be noted thatthe springs I1 and 23 are similar and parallel, the only substantialdiiference being that the upper ends of the springs 23 are secured as at24 to the outer faces of the side frame members 20, 2! of the screendeck.

It will be understood that the details of the screen and base and of themeans for vibrating the screen do not of themselves form part of thepresent invention. However, in response to rotation of the armature ofthe motor 12, the shaft 9 is rotated and the result of its rotation isthe imparting of vibration to the screen deck. For example, if the shaft9 is journaled in bearings secured in relation to the side weights 5 and6, and if it is provided with an eccentric which is in turn associatedwith the housing II, and the housing H is connected to the screen deckby the springs l5, I6, the result of rotation of the shaft 9 will be ineffect to vary the length of the connection between the side weights 5,6 and the screen deck. Thus the side weights and the screen deck will bevibrated in opposition to each other and the vibration of the screen isin practice sufficient to impart a movement of the material fed to thescreen from the screen box I along the screen even though the screen andits mesh 25 are horizontal. The path of the vibration will be determinedby the point of attachment of the springs 23 to the base frame membersI, 2, the angle at which the springs 23 are set, and the effectivelength of the springs.

It sometimes happens that substantially oversize material may go acrossthe screen, such as slabs, flat pieces or the like, or lumps which canbe broken reasonably readily. I find it advantageous to break up suchlumps or slabs or oversize particles as the material travels across thescreen and I am able to utilize the movement of the screen itself toeffect this reduction in size. The result is a very substantial increasein screening efiiciency.

I illustrate herein, for example, one or more transverse breaker plates30 which may simply be superposed upon the mesh 25 and may be secured tothe side frame members 20, 2| or to the transverse supports 22 of thescreen deck in any suitable manner. The material being conveyed alongthe screen by vibration or movement of the screen passes over theseplates 30. I oppose to each plate 30 a plurality of gravital breakerarms 3| which may be pivoted as upon rods 32 and are provided withupwardly extending portions 33, the outer ends of which are apertured tosurround the bar 32. The main body of the breaker arm 3| is generallyhorizontal with the plate 30 when a mass of material of normal thicknessis traveling across the screen or plate. The rod 32 may be mounted forexample on upwardly extending members 34 which may be secured to theside frame members I or 2 as by spacers 35, bolts 36 and nuts 31. Anysuitable spacing means for spacing the members 3| on the bars 32 may beemployed, for example spacing rings 38. End rings 39 may be secured tothe rods 32 as by pins 40 or any other suitable securing means.

It will be realized that, whereas I have described and illustrated apractical and operative device, nevertheless many changes may be made inthe size, shape, number and disposition of parts without departing fromthe spirit of my invention. I therefore wish my description and drawingsto be taken as in a broad sense illustrative or diagrammatic rather thanas limiting me to my precise showing.

It will be understood, for example, that whereas I have shown my breakerarms applied to a particular type of screen, I do not wish to be limitedto the use of my invention with any particular screen since it isapplicable to be used with a wide variety of screens. It happens to workvery well with the particular type of screen herein shown and will workequally well with widely difierent types.

I find it practical to place my members 3| adjacent the feed end of thescreen but they may be placed at any point intermediate the ends of thescreen, it being preferableof course that there be enough screen meshbeyond the crushing zone to permit eflicient screening. It is a matterof choice whether I use one or more than one row of arms.

In operation, and assuming that the screen is vibrating and that anormal feed is being maintained through the feed box 1, a layer ofmaterial undergoing separation travels from the feed to the dischargeend of the screen. This material passes over the plates 30. Thevibration of the screen itself, by moving the screen and the materialundergoing crushing upwardly against the arms 3|, causes a crushing orbreaking effect against the arms. The arms are preferably of sufficientweight to direct a substantial gravital thrust upon the top of themoving layer of material, and the vibration of the screen batters thematerial going across the plates 30 against the opposed bottom faces ofthe members 3|. Also it lifts the arms and the drop by gravity back intoposition, in a vibratory movement, causes a substantial reduction in thesize of larger particles and the results of this breaking or crushingoperation pass to the screen mesh 25 and the smaller particles passtherethrough.

It will be understood that in effect the screen by its vibration movesthe material on the screen upwardly against the hammers 3| and that theresult of the vibration of the screen is to cause a similar vibration ofthe hammers, they being lifted upwardly by the screen and then droppeddownwardly by gravity against the screen. It is important that thehammers 3| be so proportioned and pivoted and constructed as to beactually thrown upwardly by the vibration of the screen deck so thatwhen the hammers fall they will strike an effective blow. It is possibleso to select the weight and angle of support of the weight and theradius of movement of the hammer in relation to a predetermined periodof vibration of the screen that the hammers instead of rebounding willmerely follow the screen deck, thereby causing no crushing. Therefore,it is important that the hammers 3| be so proportioned that theirnatural period of spring will not coincide with the period of vibrationof the screen or with any multiple thereof. In other words, the partsare so proportioned that when the screen is vibrated the vibration ofthe hammers is at a rate or timing in relation to the timing of thevibration of the screen such that the hammer will actually strike ahammer blow against the material on the screen at each downward movementof the hammer.

One advantage of my device consists in the employment of platesintermediate the ends of the screen to serve as stratifying areas forthe material fed. I find in practice that the capacity of the screen isactually increased by the employment of these stratifying plates eventhough the actual area of the mesh effective for separation is reduced.This stratifying effect, in combination with the crushing or reducingeffect, is in practice of great importance.

I claim:

1. In combination, a screen base, a screen deck movably mounted on saidbase, means for vibrat ing said screen deck, screen mesh mounted on saiddeck, means for feeding material to be screened to said deck, a breakerplate associated with said deck, a crusher member gravitally opposed tosaid breaker plate and pivoted for movement about an axis lying in aplane above the plane of said breaker plate, and a support for saidcrusher member, to which said crusher member is journaled, said supportbeing mounted upon and upwardly extending from said screen base, saidcrusher member normally lying with a portion in contact with thematerial passing along the screen deck, its weight being sufiicient toimpart a crushing action upon the material passing over the breakerplate in response to the vibratory movement of the deck.

2. In combination, a screen base, a screen deck movably mounted on saidbase, means for vibrating said screen deck, screen mesh mounted on saiddeck, means for feeding material to be screened to said deck, a breakerplate associated with said deck, a crusher member gravitally opposed tosaid breaker plate and pivoted for movement about an axis lying in aplane above the plane of said breaker plate, and a support for saidcrusher member, to which said crusher member is journaled, said supportbeing mounted upon and upwardly extending from said screen base,

said crusher member including a portion opposed to and having a workingface generally parallel with the opposed face of the breaker plate, itsweight being sumcient to impart a crushing action upon the materialpassing over the breaker plate in response to the vibratory movement ofthe deck.

3. In combination, a screen base, a screen deck mounted on said base andmeans for vibrating said deck, screen mesh mounted on said deck, meansfor feeding material to be screened to said deck, a breaker plateassociated with said deck, a crusher member gravitally opposed to saidbreaker plate and pivoted for movement about an axis lying in a planeabove the plane of said breaker plate, and a support for said crushermember, mounted upon and upwardly extending from said screen base, saidcrusher member including a plurality of crushing hammers, a shaft onsaid support, on which said hammers are journaled, said hammers being ofsufiicient weight to impart a crushing action upon the material passingover the deck in response to the vibratory movement of the deck.

4. In combination, a screen base, a screen deck movably mounted on saidbase, means for vibrating said screen deck, screen mesh mounted on saiddeck, means for feeding material to be screened to said deck, a breakerplate associated with said deck, and located adjacent the feed end ofthe screen, a crusher member gravitally Search Room opposed to saidbreaker plate and pivoted for movement about an axis lying in a planeabove the plane of said breaker plate, and a support for said crushermember, to which said crusher member is journaled, said support beingmounted upon and upwardly extending from said screen base, said crushermember normally lying with a portion in contact with the materialpassing along the screen deck, its weight being suflicient to impart acrushing action upon the material passing over the breaker plate inresponse to the vibratory movement of the deck.

VICTOR F. LARSON.

